1. Field of the Invention
The present invention is directed to novel dihalomethylenelactones pyrethroid intermediates and to processes for the preparation thereof.
2. Description of the Prior Art
Pyrethroids show remarkable activity against various insects. Moreover, these compounds show very low mammalian toxicity which makes them extremeley useful as pesticides for crop protection. Thus bollworm species, which infest cotton, and cotton leaf worms, which are leafeating pests, are effectively combatted with pyrethroids. Pyrethroids have shown their usefulness as pesticides for fruit and vegetables protection as well. Also for animal health protection pyrethroids can successfully be applied. For example against red mites which are found in the cracks and crevices of poultry houses, particularly on perches, and which cause loss of condition by feeding on the blood of the birds. Another application of pyrethroids is against some kinds of beatles which may cause serious structural damage to buildings, especially those containing wood or polystyrene. The proved usefulness of pyrethroids stimulates Research and Development to find novel intermediates and novel economic routes to certain cyclopropanecarboxylate pyrethroids containing a dihalovinyl group.
From Journal of the American Chemical Society /88:18/ September 20, 1966, pp. 4196-4198 it is known that the reaction of succinic anhydride with sodium trichloroaectate gives 5,5,5-trichlorolevulinic acid in dimethoxyethane. In low yield (7-8%) a side product, 5,5-dichloro-4-hydroxy-2,4-pentadienoic acid lactone (dichloroprotoanemonin) is formed. This lactone comprises a conjugated system of three double bonds.